OBJECTIVES To determine whether prenatal androgen excess during early gestation in female rhesus monkeys contributes to impaired oocyte developmental competency in adulthood, as part of a study Investigating the origins of increased miscarriage in hyperandrogenic women with polycystic ovarian syndrome (PCOS). RESULTS Two prenatally androgenized rhesus monkeys with ovulatory menstrual cycles were stimulated with recombinant human FSH for collection of in vivo matured oocytes. Oocytes were aspirated laparoscopically, and inseminated in vitro following extrusion of the first polar body. Although normal numbers of oocytes were recovered from both monkeys, the proportion of mature (metaphase II) oocytes that were obtained was relatively low (approximately 31%), compared to our long-term average for normal female rhesus monkeys (76%). In one of the prenatally androgenized monkeys (#79135), none of the oocytes completed maturation before 41 hours post hCG, compared to 34 hours for normal female monkeys, and none fertilized, although numerous motile sperm were attached to the zona pellucidae 12 hours after inseminination. In the other prenatally androgenized monkey (#79169), although maturation was quite low, both the incidence of fertilization and development to the blastocyst stage were similar to controls (75% and 65%, respectively). These very preliminary data suggest that oocytes from prenatally androgenized monkeys may be impaired in their ability to mature and to fertilize. FUTURE DIRECTIONS We plan to explore whether oocytes collected from prenatally androgenized monkeys following ovarian stimulation are impaired in their capacity to mature and undergo complete preimplantation development in vitro, to provide novel insight into the high incidence of miscarriage experienced by hyperandrogenic women with PCOS. KEY WORDS oocyte, ovary, polycystic ovarian syndrome, androgen excess, miscarriage FUNDING NIH grant RR00167, UW Graduate School Research Committee, UW Medical School Committee